JMIR Publications

ABSTRACT

Background:

The advent of tirzepatide has transformed obesity care, yet real-world weight-loss outcomes necessarily depend on patient engagement with behavioral support. Digital platforms offering coaching, self-monitoring, and automated feedback have the potential to further augment pharmacological efficacy.

Objective:

To determine whether digital engagement enhances weight loss among adults prescribed tirzepatide in routine care over 12 months, and to identify baseline predictors of engagement.

Methods:

In this retrospective cohort study, we included adults (18-75 years; body mass index (BMI) ≥ 30 kg/m² or ≥ 27.5 kg/m² with comorbidities) who initiated tirzepatide between February 2024 and August 2025 via a UK digital weight-loss service (DWLS). Engagement was defined by attendance at ≥ 1 coaching session, ≥ 1 weekly weight log, and ≥ 1 app login over 12 months. Percent weight loss was analyzed at months 2, 4, 6, 8,10 and 12 using mixed-model repeated measures (MMRM) adjusted for age, sex, baseline BMI, and comorbidities. Time-to-event analyses (Kaplan-Meier) assessed attainment of ≥ 5%, ≥ 10%, ≥ 15%, and ≥ 20% weight-loss thresholds. Multivariable logistic regression identified predictors of engagement, reporting ORs per decade of age and per 5 kg/m² BMI.

Results:

Among 126,553 participants, 6,746 (5.3%) were maximally engaged. Cohort demographics: mean age 42.3 ± 12.4 years, 78.9% female, mean BMI 35.3 ± 6.2 kg/m². Engaged users achieved greater adjusted weight loss at month 12 (-22.9%; 95% CI -23.2 to -22.6) versus non-engaged users (-17.5%; 95% CI -17.7 to -17.4), an absolute difference of 5.3 pp (P< .001; Cohen's d = 0.54) and a 30.4% more relative weight loss. Differences emerged by month 2 (-7.4% vs. -6.4%; P<.001) and widened steadily. Engaged participants reached all clinically significant weight loss thresholds faster (5-20%; log-rank P<.001) and engaged participants were nearly three times more likely to achieve ≥20% weight loss compared to non-engaged participants (16.0% vs 5.6%, RR=2.88, P<.001). older age (OR 1.18 per decade; 1.15-1.20; P<.001), higher BMI (OR 1.14 per 5 kg/m²; 1.12-1.16; P<.01), and presence of PCOS (OR 1.59; 1.45-1.74; P<.001) or fatty liver disease (OR 1.52; 1.32-1.76; P<.001) predicted engagement. Male sex (OR 0.86; 0.81-0.92; P<.001) and diabetes (OR 0.83; 0.73-0.95; p = 0.009) were associated with lower engagement.

Conclusions:

Digital engagement substantially amplifies and accelerates tirzepatide-associated weight loss in real-world practice. Integrating structured digital support with pharmacotherapy represents a promising strategy for optimizing obesity management.